Low-temperature flow improves in fuels

ABSTRACT

Fuel composition: A. MIDDLE DISTILLATE FUEL B. HYDROCARBYL SUCCINAMIC ACID OR AMINE SALT THEREOF C. ETHYLENE-VINYL ACETATE POLYMER D. AROMATIC MONOCARBOXYLIC ACID E. DEMULSIFIER SELECTED FROM ALKOXY-MODIFIED METHYLENE-BRIDGED POLYALKYLPHENOLS, AMMONIA-NEUTRALIZED SULFONATED ALKYLPHENOLS, AND OXYALKYLATED GLYCOLS.

United States Patent 91 Frost, J r.

[ Nov. 26, 1974 [75] Inventor: Kenneth A. Frost, Jr., San Rafael,

Calif.

[73] Assignee: Chevron Research Company, San

Francisco, Calif.

[22] Filed: Nov. 29, 1973 [21] Appl. No.: 420,243

[52] US. Cl 44/62, 44/70, 44/71 [51] Int. Cl. C101 l/24, C101 1/22, C101 H18 [58] Field of Search 44/62, 70, 71

[56] References Cited UNITED STATES PATENTS 2.479.326 8/1949 DeVerter 44/70 3.009,792 ll/l96l Eckert et al. 44/70 3444,082 5/1969 Kautsky 44/62 3.567.639 3/197] Aaron et al..., 44/62 lllnyckyj et al. 260/873 Malec et al. 44/70 Primary ExaminerDaniel E Wyman Assistant Examinerl. Vaughn Attorney, Agent, or Firm--G. F. Magdeburger; C. J.

Tonkin; M. D. Nelson [57] ABSTRACT Fuel composition:

a. middle distillate fuel b. hydrocarbyl succinamic acid or amine salt thereof c. ethylene-vinyl acetate polymer d. aromatic monocarboxylic acid e. demulsifier selected from alkoxy-modified methylene-bridged polyalkylphenols, ammonia-neutralized sulfonated alkylphenols, and oxyalkylated glycols.

8 Claims, N0 Drawings LOW-TEMPERATURE FLOW IMPROVES IN FUELS BACKGROUND OF THE INVENTION solid or gellike, and impractical to pump. The problem is particularly acute when in-line fuel filters are employed, since these filters are ideal for trapping waxy crystals.

The flow properties of these fuels can be improved by incorporating a flow-improver additive into the fuel blend. These additives do not reduce the amount of wax which crystallizes from the fuel, but rather modify the size, shape and surface of these wax crystals by absorption and/or cocrystallization, and reduce'fluid occlusion by the crystals. This changes the wax crystal structureand permits the fluid to flow.

The use of the pour point and/or cloud point of waxy fuels to predict the flow properties of the fuel blend is not reliable. Thus, some additives which are particularly effective in depressing the pour point only moderately improve the flow properties. Alternate tests have been designed to predict the flow properties. Alternate tests have been designed to predict the flow properties of fuels. One of such tests is the Cold Filter Plugging Point Test (0-5 1238), which is widely used as a measure of low-temperature fuel operability in automotive diesel equipment.

Numerous patents have issued describing a wide number of pour point depressants which have use as flow improvers. Exemplary depressants include naphthalene alkylated with chlorinated. waxes, homoand copolymers of hydrocarbon olefms, methacrylates, vinyl esters, alkyl styrene, etc. 'One particular patent (U.S. Pat. No. 3,544,467) describes a pour point depressant also having excellent rust-inhibiting properties. This additive is an alkenyl succinamic acid which is disubstituted on the nitrogen atom with long-chain alkyl groups. It is also disclosed that these novel compounds are active as pour point depressants in combination with ethylene-olefin copolymers.

Another additive which is particularly effective in improving the flow properties of a distillate fuel is a combination of l a hydrocarbyl succinamic acid monoor di-substituted on the nitrogen with hydrocarbyl groups and (2) an ethylene/vinyl-acetate copolymer. Although this combination is most effective in improving the flow properties, it is hampered with compatibility problems when mixed in concentrates. Over prolonged periods, phase separation sometimes occurs. Also, solid lump formation occurs which necessitates heating the concentrate to redissolve the solids.

SUMMARY OF THE INVENTION Flow-improver additives for waxy hydrocarbonaceous fuels are provided, comprising an admixture of: (1 a C8 to C28 hydrocarbyl succinamic acid monoor di-substituted on the nitrogen atom with C8 to C28 hydrocarbyl groups; (2) an ethylene-vinyl acetate poly-v mer containing from 10 to 40 weight percent vinyl acetate and havinga molecular weight between 800 and about 10,000, and (3) an aromatic acid having from 7 to 20 carbons.

The succinamic acid component is prepared by reacting a hydrocarbyl succinic anhydride with a primary or secondary amine at a temperature of about to 250F. The ethylene-vinyl acetate and aromatic acid components are available commercially and can be prepared by numerous conventional processes.

The mechanism is not well understood, but generalizing from experiments with acetic acid, it appears that the carboxylic acid associates, probably through hydrogen bonding, with the succinamic acid. This hydrogen bonded complex should havegreater solubility in the additive concentrate than the free succinamic acid. This increased solubility is believed responsible for the improved compatibility of the concentrate. The aromatic acid is believed to associate with the acetate portion of the ethylene vinyl acetate copolymer thereby leading to an increased solubility of the copolymer in the concentrate.

It has been found that the employmentof the aromatic acid considerably improves the compatibility of a concentrate of the additive combination of this invention.

DETAILED DESCRIPTION OF THE INVENTION An improved additive concentrate which may be used to improve the flow properties of distillate fuels can be prepared by combining:

l. a hydrocarbyl succinamic acid having in 'a preferred embodiment the general chemical formula:

wherein R is a hydrocarbyl having from 8 to 28 carbons, preferably from 12 to 22 carbons, and from 0 to I site of olefinic unsaturation; and

X and X1 are selected from hydroxyl or a monoor di(C8 to C28 hydrocarbyl) amino radical with one of said X or Xl being hydroxyl and the other being the hydrocarbylamine radical,

2. an ethylene-vinyl acetate polymer containing from 10 to 40 weight percent vinyl acetate and having a number average molecular weight between 800 and about 10,000, and

3. a C7 to C20 aromatic carboxylic acid.

The R in the above formula is preferably a straightchain alkyl or alkenyl, exemplary of which are octyl, lauryl, hexadecyl, octadecyl, tetradecyl, heptadecyl, eiccsyl, docosyl, hexadecenyl, octadecenyl, myristyl, palmityl, stearyl, behenyl, cerotyl, palmitoleyl, oleyl, 61C.

The hydrocarbyl amino radical has preferably the following general formula:

wherein Y and (l are selected from hydrogen or an aliphatic hydrocarbyl having from 8 to 28 carbons, and preferably from 12 to 22 carbons (exemplary groups are illustrated in the definition of R, above), with at least one of said Y or Yl being an aliphatic hydrocarbyl, and preferably both of Y and Y1 being aliphatic hydrocarbyls. Y and Y1 may be aliphatically saturated or aliphatically unsaturated (alkyl or alkenyl), generally free of acetylenic unsaturation. There may be from 1 to 2 sites of olefmic unsaturation. Y and Y1 may be the same or different, and may be straight-chain or branched-chain, preferably straight-chain. The branches will normally be not greater than 1 carbon atom, i.e., methyl. The position of attachment to nitrogen may be at a terminal or internal carbon atom.

As is evidenced from the above formula, it is not important which position the alkyl or alkenyl group has in relation to the carboxamide or carboxyl group. Because of the bulky nature of the amine, however, the usual method of preparation with succinic anhydride will provide the alkyl or alkenyl group beta to the carboxamide as the major product. To the extent that this is the more easily accessible derivative, this derivative is preferred. However, as far as operability is concerned, either isomer or a mixture of the two isomers may be used.

Individual compounds or mixtures of compounds may be used as flow improvers. Mixtures of different C- and/or N-substituents, both as to homologs and thereof can be R-CHCOX2 WT FZF wherein R is as previously defined, one of the X2 and X3 is NYYl, wherein Y and Y1 have been previously defined. The other of X2 and X3 is of the formula:

wherein Y2 and Y3 may be hydrogen, aliphatic hydrocarbon of l to 30 carbon atoms or oxyaliphatic hydrocarbon (there being 1 ethereal oxygen atom present in the radical bonded to nitrogen at least beta to the nitrogen atom) of 3 to 30 carbon atoms. Y2 and Y3 may be taken together to form a heterocyclic ring of 5 to 7 members having nitrogen and oxygen as the only hetero-members. The subscript n varies from .0 to I, preferably from 0.1'to 0.9. That is, from-l to 90 mol percent of the succinamic acid present is in the form of its salt.

The aliphatic hydrocarbon groups may be saturated or unsaturated, usually having not more than 2 sites of ethylenic unsaturation. The total number of carbon atoms for HNY2Y3 will be from 0 to 60, usually 1 to 40.

The groups indicated for Y and Y] may also be used for Y2 and Y3. However, as already indicated, primary amines may be used as well as secondary amines to form the salt. Usually, where an amine other than the one used to prepare the succinamic acid is used to form the salt, as will be explained subsequently, there will be a mixture of salts; both the added amineand the secondary amine employed to prepare the succinamic acid will be involved in salt formation.

Illustrative amines which may be used to form salts are di-sec.-butylamine, heptylamine, dodecylamine, octadecylamine, tert.-butylami'ne, morpholine, diethylamine, methoxybutylamine, methoxyhexylamine, etc.

The alkenyl succinamic acids of this invention are readily prepared by reacting an alkyl or alkenyl succinic anhydride with the desired amine at a temperature in the range of about to 250F in approximately equimolar amounts, either neat or in the presence of an inert solvent. The time for the reaction is generally in the range of 15 minutes to 1 hour. This reaction is well known in the art, and does not require extensive discussion here.

The alkyl or alkenyl succinic anhydride which is used may be individual compounds or mixtures of compounds. That is, various alkyl or alkenyl groups of differing number of carbon atoms or different positions of attachment to the succinic anhydride group may be used. Alternatively, a single isomer may be used. Since mixtures are generally more readily available, to that degree they are preferred. In many instances, mixtures will be used of aliphatic hydrocarbyl-substituted succinic anhydrides where no single homolog is present in an amount greater than 25 mol percent.

Various amines may be used, both those having the same aliphatic hydrocarbon groups and those having different aliphatic hydrocarbon groups. Either alkyl or alkenyl substituents may be present on the nitrogen, each having at least 14 carbon atoms. In the preferred embodiment the range of difference between the two aliphatic hydrocarbon groups bonded at the nitrogen is not critical, but will generally be fewer than 8 carbon atoms, more usually fewer than 6 carbon atoms. For the most part, the aliphatic hydrocarbon groups will be straight-chain, i.e., normal with the amino nitrogen bonded either to internal or terminal carbon atoms.

It is found that when using approximately a 121 mol ratio of amine to succinic anhydride, depending on the reaction conditions, a significant amount of amine may be unreacted and remain to form the salt of the succinamic acid which is formed. in some instances, as much as 30 percent of the amine may remain unreacted, forming a significant amount .of salt. Thus, the salt will frequently be from 10 to 30 mol percent of the total succinamic acid present. Similarly, there may be some unreacted anhydride groups remaining in the reaction mixture which may be carried along in the flowimprover additive mixture.

Also, in situations where significant amounts of water are present during the course of the reaction, the water may react with a succinic anhydride to form succinic acid. If the temperature is not high enough to regenerate the succinic anhydride, the succinic acid will proba- I bly remain unreacted or form the amine salt with available unreacted amine. Therefore, the mixtures of succinamic acid salts may be conveniently prepared merely by using a 1:1 mol ratio of amine to succinic anhydride,

and not attempting to drive the reaction to completion, or up to a mol excess of amine.

The amine salts are readily prepared by adding the amine to the succinamic acid, conveniently as prepared, or in an inert solvent. Mild heating may facilitate the reaction.

The second component of this invention is an ethy-- lene-vinyl acetate polymer containing from to 40 weight percent, preferably from 20 to 30 weight percent, of vinyl acetate and having a number average molecular weight between 800 and about 10,000, preferably from 1,600 to 8,000, and more preferably from 2,000 to 5,000. The polymer composition can have small amounts of other monomers incorporated into or attached onto the polymeric chain. Examples of other monomers which may be employed include acrylates, methacrylates, methylol methacrylate, vinyl ethers, alpha-olefins such as propylene, isobutylene, etc., vinyl ketones, etc. These other monomers must not be present in excess of 35 weight percent of the polymer, preferably less than 20 weight percent, and more preferably less than 10 weight percent.

The polymers are commercially available, and hence a detailed description of an exemplary process is not necessary.

The third component of this invention is a C7 to C20 aromatic monocarboxylic acid. Exemplary aromatic acids include benzoic acid, p-benxyl benzoic acid, pchloro benzoic acid, o-ethoxy benzoic acid, p-ethyl benzoic acid, p-hydroxyl benzoic acid, o-isopropyl benzoic acid, o-methoxy benzoic acid, o-phenyl benzoic acid, 2, 3, 4 trimethyl benzoic acid.

The aromatic acids are commercially available and hence, a detailed description of an examplary process is not necessary.

OTHl-ZR COMPONENTS In addition to the substituted succinic acid, ethylenevinyl acetate, and aromatic acid, other additives may be present within the flow-improver concentrate and fuel. One type of additive is a demulsifier. Numerous demulsifiers are commercially available and may be employed in the practice of this invention. A particularly active demulsifier component is an alkoxymodified, methylene-bridged polyalkylphenol having the following generalized structure:

wherein U is an alkylene having from 2 m3 carbons, preferably 2; T is an alkyl of 4 to carbons, preferably 6 to 12 carbons; m is an integer of 4 to 10,,preferably 5 to 8, with at least 80 percent of the alkoxy chains being within the range specified; n1 is an integer of 2 to 10, preferably 4 to 8; and A is the same or different hydrogen or methylol (--CH2OH). Compounds having the above structure can be prepared by condensing an alkylated phenol with formal dehyde to form a methylene-bridged polyalkylated phenol, which is then contacted with an alkylene oxide such as ethylene oxide or propylene oxide. A more particularly active demulsifier is prepared by reacting 5 mols of an alkylphenol with 4-5 mols of formaldehyde,

the reaction product of which is reacted with about 30 mols of ethylene oxide.

Exemplary alkyl phenolswhich may be employed include p-isobutylphenol, p-hexylphenol, p-octylphenol, p-nonylphenol, p-tripropylenephenol, etc.

Another type of demulsifier component is an ammonia-neutralized sulfonated alkylphenol. These compounds have the general structure:

OaNH-i R1 is a hydrocarbyl having from 4 to 15 carbons,

preferably from 6 to 12.

These compounds are prepared by sulfonating an alkylated phenol and thereafter neutralizing the sulfonated product with ammonia.

Another type of demulsifier is an oxyalkylated glycol. These compounds are prepared by reacting a polyhydroxy alcohol such as ehtylene glycol, trimethylene glycol, etc., with ethylene or propylene oxide. Many of the compounds are commercially available from Wyandotte Chemical Company under the Pluronics trademark. They are polyethers terminatedby hydroxyl groups and produced by the block copolymerization of ethylene oxide and propylene oxide. The ethylene oxide blocks act as the hydrophiles and the propylene oxide blocks as the hydrophobes. They are available in a wide range of molecular weights and with varying ratios of ethylene oxide to propylene oxide blocks.

The above demulsifier components may be employed individually in mixtures. A particularly active demulsifier is a mixture of 10 to 90 parts of alkoxy-modified, methylene-bridged polyalkylphenol, 10 to 90 parts of ammonia-neutralized sulfonated alkylphenol, and 10 to 90 parts of an oxyalkylated glycol, per 100 parts of total demulsifier employed. I

The demulsifier may be added to the flow-improver additive mixture with or without the aid of a solvent.

. ticularly useful with mid-range distillate fuels.

Both naturally derived and synthetic hydrocarbon fuels may be used in conjunction with the flowv improver additives of thisinvention.

than about 2 weight percent, and frequently less than 1 weight percent, of the hydrocarbon fluid, usually in the range of 35 ppm to 1,000 ppm.

The ratio of succinamic acid to ethylene-vinyl acetate polymer will generally be about 0.25 to 50 parts of the succinamic acid to 1 part of the polymer, more usually from about 2 to 20 parts of the succinamic acid per part of polymer. The ratio of aromatic acid to succinamic acid generally varies from 0.02 to 4 parts per part and more usually from 0.1 to 2 parts per part by weight.

The flow-improver compositions may be used in the presence of various other additives which are common to compounded fuels. In addition .to the flow improver, there may be present rust inhibitors, dyes, detergents, dispersants, antioxidants, antistatic agents, metal deactivator, cetane improvers, antismoke agents, etc. Usually these other additives will be present in amounts of about 0.001 to 5 weight percent.

The following Table I illustrates the concentrations of the various components which may be present in a fuel to effectively improve the flow properties.

TABLE I FUEL COM POSITIONS 19 4 Range Hydrocarbon Fuel (wt.%) 95 100 Succinamic Acid (ppm) l0 l0,000 Ethylene-Vinyl Acetate (ppm) 1 2,000 Demulsifier (ppm) 0.1 50 Other Additives (ppm) l 20,000 Aromatic Acid (ppm) l 2,000

Preferred Range Hydrocarbon Fuel (wt.7z 98 lOO Succinamic Acid (ppm) 30 L000 Ethylene-Vinyl Acetate (ppm) 2 100 Demulsifier (ppm) 0.5 Other Additives (ppm) 0 20,000 Aromatic Acid (ppm) 1 550 'hydrocurhyl succinamic acid as defined in the formula supra.

In many instances, it is advantageous to .incorporate the flow-improver mixture into a concentrate for transportation purposes and for ease of blending into the fuel. Generally a solvent is necessary in order to maintain the concentrate in a dispersed or fluid state. Any stable organic solvent may be employed which has an appreciable solvency for the succinamic acid and ethylene-vinyl acetate components and which' is relatively inert to them. Exemplary solvents include aliphatic and aromatic hydrocarbons, aliphatic ethers, halogenated hydrocarbons, and preferably mixed aromatics (i.e., xylenes from reformate fractions) or aliphatics boiling within the range of 300-700F.

The concentrations of the various components, including the demulsifier, in the concentrate will generally range from 4 to 95 (preferably 10 to 80) parts by weight of succinamic acid component, 0.2 to 30 (preferably 2 to 25) parts by weight of the ethylene-vinyl acetate polymer. 0 to 2 (preferably 0.0] to 1.5) parts by weight of a demulsifier, 0.1 to (preferably 1 to l5) parts by weight of an aromatic acid and 0 to 95 (preferably lO to 50) parts by weight of a solvent per 100 parts of concentrate.

The following examples are presented to illustrate the practice of specific embodiments of this invention, and should not be interpreted as limitations upon the scope of this invention as defined by the appended claims.

EXAMPLE 1 This example is presented to illustrate the preparation of a preferred representative hydrocarbyl succinamic acid disubstituted on the nitrogen atom.

Twenty pounds of C15-20 l-olefins are charged into a kettle and mixed with 2%. pounds of a silica-alumina catalyst (known under the trade name of Aero Cat.). Stirring is continued for one-half hour to disperse the catalyst, and then 800 pounds of Cl5-20 l-olefins are added. Heating is started, and the mixture is kept at 400F while stirring for 3 hours. Initially the temperature of the reaction mixture rises to 425F due to the heat of the reaction. The completion of isomerization is followed by the disappearance of an infrared band at 910 crn-l. After completion of the reaction, the mixture is filtered, and the isomerized olefin is distilled under 200 mm pressure at 370F. The distillation is complete when the kettle temperature reaches 575F.

Thereafter, 510 weight parts of isomerized C 15-20 alpha-olefin as prepared above are charged to a kettle with weight parts of maleic anhydride (a molar ratio of olefin to maleic anhydride of 2:1). The mixture is purged with nitrogen, and the system is sealed. Heating and stirring are started, and the mixture is kept at 450F. The pressure in the system is about 25 psig, due to vapors of maleic anhydride. The reaction is complete in about 3 hours, and the completion is determined by the disappearance of an infrared band at 840 cm-l. The excess olefin is thereupon removed by vacuum distillation.

Thereafter, 343 parts by weight of the alkenyl succinic anhydride is charged to another kettle, along with 520 parts of di-N-(hydrogenated tallow) amine supplied by Armour Chemical Co. under the trademark Armeen 2l-IT. The mixture is heated to l50F to form the di-N-( hydrogenated tallow) alkenyl succinamic acid (DTASA). A sample of the product is isolated and characterized by titration and infrared spectrum.

EXAMPLE 2 This example is presented to illustrate the low Cold Filter PluggingPoint (CFPP) achieved by the combination of the succinamic acid and ethylene vinyl acetate copolymer. The CFPP test measures-the ability of a fuel to flow through a micronic filter element below its cloud point. The test has recently been officially accepted as a specification method relating to lowtemperature operability for critical European automotive diesel equipment. The test procedure and apparatus are described in DIN 51428 (the West German equivalent to the United States ASTM). In brief, the test comprises passing a standard volume of sample fuel through a 350 U.S. Standard Wire Mesh Filter at suc cessively decreasing temperatures. The presence of precipitated fuel wax will cause the flow rate to decrease, and eventually complete plugging of the filter will occur. The temperature at which flow finally ceases is the Cold Filter Plugging Point, and is reported to the nearest 2F.

The samples contain various amounts of an ethylenevinyl acetate copolymer, a disubstituted alkenyl succinamic acid as prepared by the method of Example 1, and various amounts of a demulsifier in a straight-run diesel gas oil (base fuel) derived from a Middle East/- North African crude source and having a cloud point at 20F. The sample fuels are tested and reported in Table ll below.

9 TABLE II COLD FILTER PLUGGING POINT TEST ADDlTlVES 1N BASE FUEL Conc. CFPP Test Type (ppm) (F.)

1 none 22 2 DTASA* 8O 22 3 DTASA* 400 22 4 Ethylene-vinyl acetate 25 14 5 Ethylene-vinyl acetate 125 12 6 Ethylene-vinyl acetate 250 12 7 DTASA 7| Ethylene-vinyl acetate# 2.5 12 Demulsifien 0.5

8 DTASA 189 Ethylene-vinyl Acetate# l5 2 Demulsifierl 1.5

9 DTASA 21 3 Ethylene-vinyl Acetate 7.5 0 Demulsificr+ 1.5

' DTASA is di-N-( hydrogenated tallovv) alkenyl succinamic acid as prepared by the method of Example I.

#Ethylene-vinyl acetate copolymcr marketed by Allied Chemical Company under brand name "A0402". The copolymer contains 25 wt. percent vinyl acetate & has a molecular weight of about 2300.

+ The dumulsifier (Tretolite Ll649) is a combination of: (l) a sulfonated alkylphcnol neutralized with ammonia: (2) an oxyalkylated glycol; and (3) an alkoity-modified. methylene-bridged polyalkylphenol.

As can be seen from the above table, theuse of the di-N-(hydrogenated tallow) alkenyl succinamic acid (DTASA) alone did not change the CFPP temperature at any concentration, while the use of the ethylenevinyl acetate only depressed the temperature 10 at a concentration of 250 ppm. The combination of 213 ppm of the DTASA with 7.5 ppm of ethylene-vinyl acetate and 1.5 ppm of demulsifier, on the other hand, de'-- pressed the CPI? temperature 22. Thus, a strong synergism between the DTASA and the ethylene-vinyl acetate in reducing the CFPP is illustrated.

EXAMPLE 3 This example is presented to illustrate the unreliability of using the pour point temperature in predicting the flow properties of a distillate fuel. in this test, the pour point is measured for each of the sample fuel blends employed in Example 2. The pour point is measured by ASTM D-97 and reported in the following Table -lll'along with the Cold Filter Plugging Point (CFPP) as shown in Example 2 for the sample fuels.

TABLE 111 POUR POlNT TEST ADDITIVES IN BASE FUEL Pour Cone. CFPP Point Blend Type (ppm) (F.) (F.)

1 none 22 2 DTASA' 80 22 5 3 DTASA' 400 22 4 EVA! 25 l4 10 5 EVA# I25 l2 l0 6 EVA 250 I2 '7 DTASA' 7| EVA! 2.5 12 0 Demulsifien 0.5

3 DTASA' 189 EVA l5 2 20 Demulsifier+ 1.5

9 DTASA' 213 EVA! -l5 TABLE lll-Continued POUR POINT TEST ADDlTlVES 1N BASE FUEL Pour Conc. CF PP Point Blend Type (ppm) (F.) (F.)

Demulsifier 1.5

'DTASA defined in Table II #EVA (ethylene-vinyl acetate) defined in Table 11 +Demulsifier defined in Table 11 The above table illustrates the failure of the pour point measurement to determine the flow properties of a distillate fuel. A comparison of Test Blends 3 and 8 show that both compositions have equivalent pour points; however, Blend 8 is far superior to Blend 3 in flow properties.

EXAMPLE 4 This example is presented to illustrate the superior water-tolerance properties of the combination of this invention. In this test, 300 milliliters of the sample fuel are placed in a high-speed blender (Waring Co.) along with 3 m1 of sea water. The contents are stirred at 7,000

.rpm for 30 seconds. The mixture is visually observed after sitting quiescent for 1 hour and for 24 hours. The

fuel haze is rated on a scale of 1 to 5, with 1 being bright and clear and 5 being cloudy.

The sample fuels containvarious amounts of an ethylene-vinyl acetate copolymet a disubstituted alkenyl succinamic acid and a demulsifier, in a straight-run diesel gas oil derived from a Middle East/North African crude source and having a cloud point at 20F. The sample fuels are subjected to the above test and the haze measured and reported in the following Table IV.

TZBLE 1V WATER TOLERANCE PROPERTlES 'DTASA defined in Table ll IEVA (ethylene-vinyl acetate) defined in Table I1 i'Demulsifier defined in Table II.

In the above Table 1V, a comparison of Blends l, 2, 3 and 4 illustrates that the combination (Blend 4) of demulsifier and DTASA has a remarkable fuel haze rat- .ing of 2 after one hour and 1 after 24 hours, whereas the individual components in the fuel could rate no better than after one hour and 3 after 24 hours. A comparison of Blends 2, 5, 6, 7 and 8 with Blend 9 illustrates that the combination of DTASA, ethylenevinyl acetate and demulsifier is superior in haze rating to the individual components. EXAMPLE 5 This example is presented to illustrate the preparation of a preferred combination. A sample fuel is prepared by combining:

l. an ethylene-vinyl acetate polymer (referred to in Table V as EVA polymer), having an approxil mate molecular weight of 2,350 and containing about 25 weight percent vinyl acetate (the polymer is also believed to contain minor amounts of a third component). The polymer is marketed by Apollo Chemical Company as a 25 weight percent solution in an aromatic solvent under the brand name Apollo WD-22;

2. a di-N-(hydrogenated tallow) alkenyl succinamic 5 lene-vinyl acetate copolymer as described in Example 5, and 1 weight percent of a demulsifier marketed by Tret'olite Corporation under the brand name L-l644 and (B) parts by weight of a compatibility improver.

0 The samples are prepared and allowed to remain qui- TABLE VI COMPATlBlLlTY TEST Test Com atibilit Vol. 7: acid (referred to m Table V as DTASA as pre- Nu z Residue Quiescent period pared by the method of Example 1; and 0 Non 10 I 4 s 3. approximately 1 weight percent of a demulsifier i Acid l g (Tretolite L-l644); genzolicAAcig l 1 g ll montli1 enzy co 0 mont in various base fuels. cyclohexanone 3 2 days The compositions and the Cold Filter Plugging point Oleic Acid 8 2 days for each sample fuel are presented in the following 25 8 2 days Table V Nitrobenzene 3 2 days TABLE V COMPOSITIONS Cone. CFPP Blend Base Fuel Additive (ppm) ("F) l Diesel fuel A 20 2 Diesel fuel A DTASA 8O 8 EVA polymer 20 3 Diesel fuel A DTASA 240 2 EVA polymer 6() 4 Diesel fuel B l7 5 Diesel fuel B DTASA 80 I2 EVA polymer 2O 6 Diesel fuel B DTASA 240 7 EVA polymer 7 Light heating oil C 20 8 Light heating oil C DTASA 240 4 EVA polymer 60 9 Diesel gas oil D i l5 l0 Diesel gas oil D DTASA 240 8 EVA polymer 60 l l Light heating oil E 24 12 Light heating oil E DTASA 240 9 EVA polymer 60 [3 Middle Distillate Fuel F l4 l4 do.

Fuel F DTASA 240 4 l5 do. EVA polymer 60 Fuel F DTASA 216 4 EVA polymer 54 Benzoic Acid 30 16 Middle Distillate Fuel G 24 17 do.

Fuel G DTASA 240 4 EVA polymer 60 18 do.

Fuel G DTASA 2l6 4 EVA polymer 54 Benzoic Acid 30 All base fuels are straight-run distillates in the boiling range of 300750F. produced from blends of Arabian and North African crudes. The cloud points of these fuels are in the range of EXAMPLE 6 This example is presented to demonstrate the effectiveness of the aromatic acid in improving the compatibility of the hydrocarbyl succinamic acid and 'ethylene/vinyl-acetate flow improver of this invention.

Several experimental test samples are prepared and subjected to a centrifuge test. Those samples yielding a less than 2 volume percent of residual material are M As can be seen from the above table, the addition of benzoic acid substantially reduced the amount of residue separated by the centrifuge. A low amount of resil. a C8 to C28 hydrocarbyl succinamic acid monoor disubstituted on the nitrogen atom with C8 to C28 hydrocarbyl groups or a C l and C30 hydrocarbyl amine salt thereof or mixtures thereof,

2. an ethylene-vinyl acetate polymer containing from 10 to 40 weight percent vinyl acetate and having a molecular weight between 800 and about 10,000; and

3. a C7 to C20 aromatic monocarboxylic acid;

wherein said succinamic acid is present in an amount from 0.25 to 50 weight parts for each weight part of said polymer and said aromatic monocarboxylic acid is present in an amount from 0.02 to 4 weight parts for each weight part of said succinamic acid.

2. The composition defined in claim 1 wherein said succinamic acid has the following general formula:

R is a C8 to C28 hydrocarbyl having from to 1 site of olefinic unsaturation; and

X and XI are selected from hydroxyl or a monoor di(C8 to C28 hydrocarbyl) amino radical, with one of said X or Xl being hydroxyl and the other X or Xl being a monoor di(C8 to C28 hydrocarbyl) amino radical.

3. The composition defined in claim 2 wherein said succinamic acid is present in an amount from 2 to 20 weight parts for each weight part of said polymer and said aromatic acid is present, in an amount from 0.1 to 2 weight parts for each weight part of said succinamic acid.

4. The composition defined in claim 2 wherein from 0.1 to 50 parts per million of a demulsifier selected from the group consisting of alkoxy-modified, methylene-bridged polyalkylphenol, an ammonia-neutralized sulfonated alkylphenol, an oxyalkylated glycol, or mixtures thereof is also present in said admixture.

5. The composition defined in claim 1 wherein said aromatic acid is benzoic acid.

6. A fuel composition comprising a major portion of a middle distillate hydrocarbon fuel and a lowtemperature, flow-improving amount of an admixture of:

1. a succinamic acid or amine salt thereof or mixtures thereof having the general structural formula:

wherein R is a C8 to C28 hydrocarbyl having from 0 to 1 site of olefinic unsaturation;

X and X1 are selected from hydroxyl or OH(N- l-ly2y3) or a di-C8 to C28 hydrocarbyl sec-amino radical, with one of said X or Xl being hydroxyl or OH(Nl-ly2y3) and the other being said secamino radical;

y2 and y3 are the same or different constituents selected from hydrocarbyl having from one to 20 carbons or alkoxy having from three to 30 carbons and may be taken together with the nitrogen to which they are attached to form a heterocyclic ring of five to seven annular members;

2. a demulsifier selected from an alkoxy-modified,

methylene-bridged polyalkylphenol having the for- A I i J T m T wherein so un wherein R is a hydrocarbyl having from four to 15 carbons;

or an oxyalkylated glycol; or mixtures thereof; I 3. an ethylene-vinyl acetate copolymer containing from 10 to 40 weight percent of vinyl acetate and I having a molecular weight from 800 to 10,000; and

4. a C7 to C20 aromatic monocarboxylic acid, wherein said succinamic acid is present in an amount from 0.25 to 50 weight parts for each weight part of said polymer and said aromatic acid is present in an amount from 0.02 to 4 weight parts 7 for each weight part .of succinamic acid.

7. A fuel composition comprising:

1. at least weight percent of a middle distillate hydrocarbon fuel;

2. from 10 to 10,000 parts per million of a C8-C28 hydrocarbyl succinamic acid disubstituted on its nitrogen atom with C8-C28 hydrocarbyl groups or Cl-C30 hydrocarbyl amine salt thereof, or mixtures thereof;

3. from 1 to 2,000 parts per million of an ethylenevinyl acetate polymer containing from 10 to 40 weight percent of vinyl acetate and having a molecular weight from 800 to about 10,000;

4. from 0.1 to 50 parts per million of a demulsifier selected from an alkoxy-modified, methylenebridged polyalkylphenol, an ammonia-neutralized sulfonated alkylphenol, an oxylalkylated glycol, or mixtures. thereof; I

5. from 1 to 2,000 parts per million of a C7-C2O aromatic monocarboxylic acid.

8. The fuel composition defined in claim 7 wherein said aromatic acid is benzoic acid.

P040510 Q 4 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN Patent No. 3, 5 ,5 7 Dated November 26, 197A Inventor s v KENNETH A. FROST, JR.

It is certified that error appears in theabove-identified patent and that said Letters Patent are hereby corrected as shown below:-

Title page, line 1, the title of-che patent should read --.'-LOWTEMPERATURE FLOW-IMPROVERS IN FUELS--.

Col. 5, line 3 1, "examplary" should read '--exemplary--.

Col. 6, line 3, "A more particularly" should read A particularly-- v Col. 11, Table V; in column headed "Blend" NO'QT 'Light heating oil C 20 should read -Light heatingoil C 20--.

' I! II I Col. 13, line V3, C and C should read C to C Signed and sealed this 11th day of March v1975 (SEAL) Attest:

C. MARSHALL DANN Commissioner of Patents an'd'Tra'demarks RUTHQC. MASON Attesting Offic 

1. A FLOW-IMPROVER COMPOSITION COMPRISING A MIXTURE OF
 1. A C8 TO C28 HYDROCARBYL SUCCINAMIC ACID MONO- OR DISUBSITUTED ON THE NITROGEN ATOM WITH C8 TO C28 HYDROCARBYL GROUPS OR A C1 TO C30 HYDROCARBYL AMINE SALT THEREOF OR MIXTURES THEREOF,
 2. AN ETHYLENE-VINYL ACETATE POLYMER CONTAINING FROM 10 TO 40 WEIGHT PERCENT VINYL ACETATE AND HAVING A MOLECULAR WEIGHT BETWEEN 800 AND ABOUT 10,000; AND
 2. an ethylene-vinyl acetate polymer containing from 10 to 40 weight percent vinyl acetate and having a molecular weight between 800 and about 10,000; and
 2. The composition defined in claim 1 wherein said succinamic acid has the following general formula:
 2. a demulsifier selected from an alkoxy-modified, methylene-bridged polyalkylphenol having the formula:
 2. from 10 to 10,000 parts per million of a C8-C28 hydrocarbyl succinamic acid disubstituted on its nitrogen atom with C8-C28 hydrocarbyl groups or C1-C30 hydrocarbyl amine salt thereof, or mixtures thereof;
 3. from 1 to 2,000 parts per million of an ethylene-vinyl acetate polymer containing from 10 to 40 weight percent of vinyl acetate and having a molecular weight from 800 to about 10,000;
 3. an ethylene-vinyl acetate copolymer containing from 10 to 40 weight percent of vinyl acetate and having a molecular weight from 800 to 10,000; and
 3. The composition defined in claim 2 wherein said succinamic acid is present in an amount from 2 to 20 weight parts for each weight part of said polymer and said aromatic acid is present in an amount from 0.1 to 2 weight parts for each weight part of said succinamic acid.
 3. a C7 to C20 aromatic monocarboxylic acid; wherein said succinamic acid is present in an amount from 0.25 to 50 weight parts for each weight part of said polymer and said aromatic monocarboxylic acid is present in an amount from 0.02 to 4 weight parts for each weight part of said succinamic acid.
 3. A C7 TO C20 AROMATIC MONOCARBOXYLIC ACID; WHEREIN SAID SUCCINAMIC ACID IS PRESENT IN AN AMOUNT FROM 0.25 TO 50 WEIGHT PART FOR EACH WEIGHT PART OF SAID POLYMER AND SAID AROMATIC MONOCARBOXYLIC ACID IS PRESENT IN AN AMOUNT FROM 0.02 TO 4 WEIGHT PARTS FOR EACH WEIGHT PART OF SAID SUCCINAMIC ACID.
 4. The composition defined in claim 2 wherein from 0.1 to 50 parts per million of a demulsifier selected from the group consisting of alkoxy-modified, methylene-bridged polyalkylphenol, an ammonia-neutralized sulfonated alkylphenol, an oxyalkylated glycol, or mixtures thereof is also present in said admixture.
 4. a C7 to C20 aromatic monocarboxylic acid, wherein said succinamic acid is present in an amount from 0.25 to 50 weight parts for each weight part of said polymer and said aromatic acid is present in an amount from 0.02 to 4 weight parts for each weight part of succinamic acid.
 4. from 0.1 to 50 parts per million of a demulsifier selected from an alkoxy-modified, methylene-bridged polyalkylphenol, an ammonia-neutralized sulfonated alkylphenol, an oxylalkylated glycol, or mixtures thereof;
 5. from 1 to 2,000 parts per million of a C7-C20 aromatic monocarboxylic acid.
 5. The composition defined in claim 1 wherein said aromatic acid is benzoic acid.
 6. A fuel composition comprising a major portion of a middle distillate hydrocarbon fuel and a low-temperature, flow-improving amount of an admixture of:
 7. A fuel composition comprising:
 8. The fuel composition defined in claim 7 wherein said aromatic acid is benzoic acid. 